Why did the Joker lick his lips?This answer does provide useful insight, but still only sort of answers the question. We only know that Nolan didn't direct him to do it. The dream solution: Ledger commenting on it. +1 pending more info.

How do the Dallas movies fit between the old and new shows?Some constructive criticism: you're asking a few different questions here. One about continuity between an old project and a rebooted one, and another about viewing order/relevance. Also: the interview cited in that Wiki article answers your question about continuity, definitively, from a writer/executive producer for the show.